Longitudinal quantitative MRI assessment of cortical damage in multiple sclerosis: A pilot study

Area of Science:

• Neuroimaging
• Radiology
• Biomedical Engineering

Background:

• Multiple sclerosis (MS) involves cortical pathology affecting microstructural integrity.
• Quantitative MRI (qMRI) measures T1-relaxation time and proton density (PD) to assess cortical changes.
• Longitudinal changes in MS cortical tissue using qMRI have not been previously investigated.

Purpose of the Study:

• To longitudinally assess cortical tissue changes in MS patients using qMRI.
• To compare qMRI-derived microstructural changes with cortical atrophy measured by conventional MRI.

Main Methods:

• Twelve relapsing-remitting MS patients underwent 3T T1/PD-mapping at two timepoints (12-month interval).
• Cortical T1/PD values were extracted from the cortical layer.
• Cortical thickness was measured for surface-based analysis of longitudinal changes.

Main Results:

• Statistically significant clusters showed increasing PD and T1 values over time (T1: 3.4%/year, P=0.0007; PD: 2.3%/year, P=0.01).
• Longitudinal changes were heterogeneous across the cortex, with varying patterns of PD and T1 increase.
• Cortical thickness analysis revealed only one small cluster with decreased thickness.

Conclusions:

• qMRI detects spatially inhomogeneous, multifocal increases in PD and T1 values in MS cortical tissue.
• Increased PD suggests neural tissue replacement by water; increased T1 indicates demyelination, axonal loss, and gliosis.
• qMRI changes are more pronounced than cortical atrophy, highlighting its potential for detecting subtle microstructural alterations in MS.